U.S. patent application number 12/664541 was filed with the patent office on 2010-07-08 for optical filter for display, and display and plasma display panel provided with the optical filter.
This patent application is currently assigned to BRIDGESTONE CORPORATION. Invention is credited to Hideyuki Kamei, Hiroshi Nakamura, Masato Sugimachi.
Application Number | 20100172028 12/664541 |
Document ID | / |
Family ID | 40129742 |
Filed Date | 2010-07-08 |
United States Patent
Application |
20100172028 |
Kind Code |
A1 |
Kamei; Hideyuki ; et
al. |
July 8, 2010 |
OPTICAL FILTER FOR DISPLAY, AND DISPLAY AND PLASMA DISPLAY PANEL
PROVIDED WITH THE OPTICAL FILTER
Abstract
An optical filter for a display having both excellent antiglare
property and transparency, and a process for producing the optical
filter are provided. The optical filter of the invention includes:
a structure including a film and a mesh-shaped metal conductive
layer provided on one surface of the film; and an antiglare layer
provided on the one surface of the mesh-shaped metal conductive
layer, the antiglare layer including a resin and fine particles
dispersed in the resin, the fine particles protruding from the
surface of the antiglare layer. In addition, the optical filter of
the invention includes: a structure including a film and a
mesh-shaped metal conductive layer provided on one surface of the
film; a sealing layer for filling spaces of the mesh defined by the
mesh-shaped metal conductive layer, the sealing layer being
provided on the one surface of the mesh-shaped metal conductive
layer; and an antiglare layer provided on the sealing layer, the
antiglare layer including a resin and fine particles dispersed in
the resin, the fine particles protruding from the surface of the
antiglare layer.
Inventors: |
Kamei; Hideyuki;
(Yokohama-shi, JP) ; Nakamura; Hiroshi;
(Yokohama-shi, JP) ; Sugimachi; Masato;
(Yokohama-shi, JP) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W., SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
BRIDGESTONE CORPORATION
Chuo-ku, Tokyo
JP
|
Family ID: |
40129742 |
Appl. No.: |
12/664541 |
Filed: |
June 13, 2008 |
PCT Filed: |
June 13, 2008 |
PCT NO: |
PCT/JP2008/060872 |
371 Date: |
December 14, 2009 |
Current U.S.
Class: |
359/609 |
Current CPC
Class: |
G02B 5/0226 20130101;
H01J 11/10 20130101; H05K 9/0094 20130101; G02B 5/0278 20130101;
G02B 5/0268 20130101; G02B 5/0294 20130101; H05K 9/0054 20130101;
H01J 11/44 20130101; G02B 5/204 20130101 |
Class at
Publication: |
359/609 |
International
Class: |
G02B 27/00 20060101
G02B027/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2007 |
JP |
2007-159124 |
Claims
1. An optical filter for a display comprising: a structure
comprising a film and a mesh-shaped metal conductive layer provided
on one surface of the film; and an antiglare layer provided on the
one surface of the mesh-shaped metal conductive layer, the
antiglare layer comprising a resin and fine particles dispersed in
the resin, the fine particles protruding from the surface of the
antiglare layer.
2. An optical filter for a display comprising: a structure
comprising a film and a mesh-shaped metal conductive layer provided
on one surface of the film; a sealing layer for filling spaces of
the mesh defined by the mesh-shaped metal conductive layer, the
sealing layer being provided on the one surface of the mesh-shaped
metal conductive layer; and an antiglare layer provided on the
sealing layer, the antiglare layer comprising a resin and fine
particles dispersed in the resin, the fine particles protruding
from the surface of the antiglare layer.
3. An optical filter for a display as defined in claim 1, wherein
thickness of the antiglare layer is smaller than the mean particle
size of the fine particles.
4. An optical filter as defined in claim 1, wherein one of the
antiglare layer and a combination of the sealing layer and the
antiglare layer is formed by applying a coating liquid comprising
an organic solvent, the fine particles and the resin being
dispersed in the organic solvent.
5. An optical filter as defined in claim 1, wherein the haze value
of the filter is not more than 10%.
6. An optical filter as defined in claim 1, wherein the fine
particles are organic resin particles or inorganic particles.
7. An optical filter as defined in claim 6, wherein the organic
resin particles are at least one kind of particles selected from a
group consisting of cross-linked acrylic resin particles,
cross-linked styrene resin particles and cross-linked
acrylic-styrene copolymer particles.
8. An optical filter as defined in claim 1, wherein the resin in
the antiglare layer is a ultraviolet curable resin.
9. An optical filter as defined in claim 1, wherein the refractive
index of the resin in the antiglare layer is free from a
substantial difference from that of the fine particles therein.
10. An optical filter as defined in claim 1, wherein the difference
between the refractive index of the resin in the antiglare layer
and that of the fine particles is not more than 0.03.
11. An optical filter as defined in claim 2, wherein the sealing
layer has the same composition as that of the antiglare layer
12. An optical filter as defined in claim 1, wherein the antiglare
layer functions as a hard coat layer.
13. An optical filter as defined in claim 1, wherein the mean
height from the surface of the antiglare layer to the surface of
the protruded fine particles is 10 to 40% of the mean particle size
of the fine particles.
14. An optical filter for a display as defined in claim 1, wherein
the transmission image sharpness established in JIS-K-7105 is not
less than 150.
15. An optical filter for a display as defined in claim 1, wherein
the reflection image sharpness (reflection angle: 45 degrees)
established in JIS-K-7105 is not more than 100.
16. An optical filter for a display as defined in claim 1, wherein
the surface roughness (Ra) of the antiglare layer is in the range
of about 0.05 to about 0.6 .mu.m.
17. An optical filter for a display as defined in claim 1, wherein
the optical filter is used as a plasma display panel optical
filter.
18. An optical filter for a display as defined in claim 1, further
comprising a glass substrate, and the film in the structure being
provided on the glass substrate so that the other surface of the
substrate is in contact with a surface of the glass substrate.
19. A display comprising the optical filter for a display as
defined in claim 1.
20. A plasma display panel comprising the optical filter for a
display as defined in claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an optical filter for
adding various functions such as antireflection, near-infrared
shielding and electromagnetic wave shielding to various displays
such as plasma display panel (PDP), cathode-ray-tube (CRT) display,
liquid crystal display, organic EL (FED) electroluminescence
display and field emission display (FED) including
surface-conduction electron-emitter display (SED), and a display
provided with the optical filter, particularly PDP.
[0003] 2. Description of the Related Art
[0004] In flat-panel displays such as a liquid crystal display,
plasma display panel (PDP) and organic EL display, and CRT Display,
a problem is known that external light is reflected on a surface of
the display and creates difficulty to see visual information on the
display. Therefore, various countermeasures including provision of
various optical films such as an antireflection film on the
displays are taken.
[0005] In recent years, image magnification has entered the
mainstream of the displays, and use of next-generation PDP has been
generalized. However, the PDP high-frequency wave pulse discharge
is carried out in the light emitting part of the PDP for displaying
image. Therefore, unnecessary electromagnetic waves or infrared
rays which cause malfunction of infrared remote controls are
possibly radiated. Thus, for this purpose, as for the PDP, various
antireflection conductive films (electromagnetic wave shielding and
light transmissive materials) for PDP have been proposed. Examples
of the electromagnetic wave shielding light transmitting materials
include (1) a transparent film having a metallic silver-containing
trans-parent conductive thin layer thereon; (2) a transparent film
having a conductive mesh layer consisting of network-patterned
metallic wire or conductive fiber thereon; (3) a transparent film
having network-patterned copper foil layer obtained by
etching-processing copper foil so as to have opening parts thereon;
and (4) a transparent film having a mesh-shaped conductive ink
layer formed by printing thereon.
[0006] In addition, since visibility of an image displayed on a
display is decreased when a surface of a filter is scratched, a
filter for a display having a hard coat layer is known.
Furthermore, in a large size display including a conventional PDP,
there has been a problem that it is hard to watch the image
displayed on the display due to reflection of rays radiated from an
external light source such as a fluorescent lamp. Therefore, a
filter for a display having an antireflection layer is widely
used.
[0007] A laminated filter for a display may include an
electromagnetic wave shielding layer, a hard coat layer and an
antireflection layer, depending upon an application. For example,
JP2004-163752 discloses a filter for a display in which an
electromagnetic wave shielding layer, a hard coat layer and an
antireflection layer are laminated in this order on a transparent
substrate.
[0008] Further, JP2002-374094 discloses a filter for a display in
which a lattice-shaped antiglare layer is provided on a transparent
substrate and a lattice-shaped conductive layer is provided on the
antiglare layer. As an illustrated antiglare layer, a black ink
layer in which inorganic pigment such as carbon black is dispersed
in a synthetic resin such as urethane resin and acrylic resin.
DISCLOSURE OF THE INVENTION
Problem to be Solved by the Invention
[0009] It is desirable to improve the antiglare property of a
conventional filter for a display. That is to say, it is sometimes
difficult to recognize images, such as letters, on the display in a
room, because of the reflection of light, e.g., from a fluorescent
lamp. Therefore, it is desired that the filter has an improved high
anti-glare property, in order to prevent the display from
reflecting off of the external environment.
[0010] In order to obtain a high antiglare property, JP2002-374094,
for example, proposes the provision of a black antiglare layer
under a mesh conductive layer. There was a possibility, however,
that the black anti-glare layer does not ensure sufficient
transparency because of reduction of haze in the anti-reflection
layer.
[0011] Thus, an object of the present invention is to provide an
optical filter having both excellent antiglare property and
transparency.
[0012] Further, another object of the invention is to provide an
optical filter, which can be easily prepared, having both excellent
antiglare property and transparency.
[0013] A further object of the invention is to provide an optical
filter for a display, which can be easily prepared and is light and
thin, having both excellent antiglare property and transparency,
and good electromagnetic wave shielding property.
[0014] A still another object of the present invention is to
provide an optical filter suitable for PDP, which can be easily
prepared, having both excellent antiglare property and transparency
and good electromagnetic wave shielding property.
[0015] Yet another object of the present invention is to provide a
display wherein the above-mentioned optical filter having excellent
properties is attached to a surface of a glass plate for displaying
images included in the display.
[0016] Yet another object of the present invention is to provide a
plasma display panel (PDP) wherein the above-mentioned optical
filter having excellent properties is attached to a surface of a
glass plate for displaying images included in the display.
Means for Solving Problem
[0017] The present invention provides:
[0018] An optical filter for a display comprising:
[0019] a structure comprising a film (generally, one transparent
film) and a mesh-shaped metal conductive layer provided on one
surface of the film; and
[0020] an antiglare layer provided on the one surface of the
mesh-shaped metal conductive layer, the antiglare layer comprising
a resin and fine particles dispersed in the resin, the fine
particles protruding from the surface of the antiglare layer;
and
[0021] an optical filter for a display comprising:
[0022] a structure comprising a film and a mesh-shaped metal
conductive layer provided on one surface of the film;
[0023] a sealing layer for filling spaces of the mesh defined by
the mesh-shaped metal conductive layer, the sealing layer being
provided on the one surface of the mesh-shaped metal conductive
layer; and
[0024] an antiglare layer provided on the sealing layer, the
antiglare layer comprising a resin and fine particles dispersed in
the resin, the fine particles protruding from the surface of the
antiglare layer.
[0025] In the former optical filter, the thickness of the antiglare
layer is preferably greater than the height of the mesh in the
metal conductive layer by 1 .mu.m or more.
[0026] The above-mentioned height from the surface of the film to
the surface of the antiglare layer (the thickness of the antiglare
layer) is calculated from the difference obtained by measuring the
surface of the film and the surface of the antiglare layer formed
on the surface of the film, by using a surface roughness meter
(trade name: SURFCOM480A available from Tokyo Seimitsu Co., Ltd),
in accordance with JIS B0601-2001.
[0027] The height from the surface of the antiglare layer to the
surface of the exposed fine particles (hereinafter, referred to as
particles) can be calculated from a profile curve obtained by
measuring by using the surface roughness meter (trade name:
SURFCOM480A available from Tokyo Seimitsu Co., Ltd) in accordance
with JIS B0601-2001. This was carried out at the measurement length
of 2 mm.
[0028] Preferred embodiments of the optical filter for a display
according to the present invention are described as follows:
[0029] (1) The thickness of the antiglare layer is smaller than
mean particle size of the particles. Hence, the antiglare layer
having excellent antiglare property can be easily prepared.
[0030] (2) The antiglare layer, or the combination of the sealing
layer and the antiglare layer can be formed by applying a coating
liquid comprising the resin and the particles dispersed in an
organic solvent.
[0031] (3) The particles have a mean particle size of 1 to 10
.mu.m.
[0032] (4) The particles are organic resin particles or inorganic
particles. The organic resin particles are preferred, and
particularly at least one kind of particles selected from a group
consisting of cross-linked acrylic resin particles, cross-linked
styrene resin particles and cross-linked acrylic-styrene copolymer
particles are preferred.
[0033] The inorganic particles are at least one kind of metal oxide
particles selected from the group comprising ITO, TiO.sub.2,
ZrO.sub.2, CeO.sub.2, SiO.sub.2, Al.sub.2O.sub.3, Y.sub.2O.sub.3,
La.sub.2O.sub.3 LaO.sub.2 and Ho.sub.2O.sub.3.
[0034] (5) Resin of the antiglare layer is ultraviolet curable
resin.
[0035] (6) In the antiglare layer, there is substantially no
difference between the refractive index of the resin in which the
particles are dispersed and that of the particles, particularly not
more than 0.03. Based on this, the transparency of the antiglare
layer can be enhanced
[0036] (7) The sealing layer has the same composition as that of
the anti-glare layer. The antiglare property can be stably
obtained. Further, productivity is also enhanced.
[0037] (8) The antiglare layer functions as a hard coat layer. It
is not necessary to form a hard coat layer.
[0038] (9) The mean height from the surface of the antiglare layer
to the surface of the protruded particles is in the range of 10 to
50%, particularly in the range of 10 to 40% based on the mean
particle size of the particles.
[0039] (10) The mesh-shaped metal conductive layer has a thickness
of 1 to 15 .mu.m.
[0040] (11) Transmission image sharpness established in JIS-K-7105
is not less than 150. (The determination is carried out, in
general, with respect to a laminate comprising a film, a conductive
layer and an antiglare layer or a laminate comprising a film, a
conductive layer, a sealing layer and an anti-glare layer.)
[0041] (12) Reflection image sharpness (reflection angle: 45
degrees) established in JIS-K-7105 is not more than 100. (The
determination is carried out, in general, with respect to a
laminate comprising a film, a conductive layer and an antiglare
layer or a laminate comprising a film, a conductive layer, a
sealing layer and an antiglare layer.)
[0042] (13) Surface roughness (Ra) of the antiglare layer is in the
range of 0.05 to 0.6 .mu.m. It was determined by using a surface
roughness meter (trade name: SURFCOM 480A, available from TOKYO
SEIMITSU Co., Ltd) in accordance with JIS B0601-2001.
[0043] (14) The film is a transparent plastic film.
[0044] (15) The optical filter for a display is an optical filter
for a plasma display panel.
[0045] (16) The optical filter for a display is an optical filter
for a display attached to a glass plate.
[0046] Furthermore, the present invention also provides:
[0047] a display comprising the abovementioned optical filter for a
display (generally speaking, the optical filter is attached to a
surface of a glass plate for displaying images); and
[0048] a plasma display panel comprising the abovementioned optical
filter for a display (generally speaking, the optical filter is
attached to a surface of a glass plate for displaying images).
[0049] It is preferred that the optical filter for a display is
attached to an image-displaying glass plate by bonding the surface
which does not carry the conductive layer to the surface of the
image-displaying glass plate.
EFFECT OF THE INVENTION
[0050] According to the present invention, an optical filter
suitable for a display can be obtained by forming a sealing layer
for filling spaces defined by a mesh shaped metal conductive layer.
The sealing layer is provided on the surface of the mesh-shaped
conductive layer, and an antiglare layer, from which particles are
exposed, can be prepared on the sealing layer. Such optical filter
of the invention is stable and has excellent anti-glare property
and transparency. Further, an optical filter suitable for a display
having excellent antiglare property and transparency can be easily
obtained by forming an antiglare layer, from which particles are
exposed, on a surface of a mesh-shaped conductive layer.
[0051] Therefore, the optical filter of the present invention is
excellent in visibility of image displayed on a display, and is
useful as a filter for a display attached to the surface of optical
products such as plasma display panel (PDP) and EL display.
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] FIG. 1 is a partial schematic sectional view showing a
representative example of an optical filter for a display according
to the present invention.
[0053] FIG. 2 is a partial enlarged sectional view showing the
optical filter for a display shown in the FIG. 1.
[0054] FIG. 3 is a partial schematic sectional view showing another
representative example of the optical filter for a display
according to the present invention.
[0055] FIG. 4 is a partial schematic sectional view showing an
embodiment of the optical filter for a display according to the
present invention.
[0056] FIG. 5 is a schematic sectional view showing an embodiment
of the optical filter for a display according to the present
invention.
[0057] FIG. 6 is a plane view showing the optical filter for a
display with the electrode part shown in the FIG. 5.
[0058] FIG. 7 is a schematic sectional view showing an embodiment
of an optical filter, wherein of a state that the optical filter
according to the present invention is attached to image-displaying
surface of plasma display panel, a kind of display.
EXPLANATION OF REFERENCE NUMBER
[0059] 11, 31, 41 Transparent film [0060] 12, 42 Sealing layer
[0061] 13, 33, 43 Conductive layer [0062] 14, 34, 44 Antiglare
layer [0063] 15, 45 Low refractive index layer [0064] 16, 46
Near-infrared absorption layer [0065] 17, 47 Transparent adhesive
layer
DESCRIPTION OF PREFERRED EMBODIMENTS
[0066] The optical filter of the present invention is explained by
referring to the figures.
[0067] FIG. 1 is a schematic sectional view (central fragmentary
view) of the optical filter of the present invention.
[0068] The optical filter of the present invention comprises a
transparent film 11, a mesh-shaped conductive layer
(electromagnetic wave shielding layer) 13 formed on the transparent
film 11, a sealing layer 12 for filling spaces of the mesh of the
conductive layer 13, and an antiglare layer 14 formed on the
conductive layer 13 and the sealing layer 12 (in case the
conductive layer 13 is covered with the sealing layer 12, formed on
the sealing layer 12). The antiglare layer 14 contains particles
14A therein, which protrude from the surface of the antiglare layer
14.
[0069] In the present invention, firstly, the spaces defined by the
mesh-shaped conductive layer 13 is filled by the sealing layer 12,
to obtain a substantially flat surface. Then, the thin antiglare
layer 14 is formed such that the particles 14A protrude from the
surface thereof. Thereby, an uneven surface can be easily formed,
and the degree of unevenness can be easily controlled. For
providing the sealing layer, the antiglare layer preferably has a
thickness of 1 to 8 .mu.m, particularly 1 to 5 .mu.m.
[0070] In order to form the antiglare layer wherein the particles
are dispersed in the resin and are protruded from the surface, the
thickness of the antiglare layer is preferably smaller than the
mean particle size of the particles. Accordingly, the antiglare
layer, which has excellent antiglare property, can be easily
prepared. If the particles are protruded from the anti-glare layer,
the thickness of the antiglare layer can also be larger than the
mean particle size of the particles.
[0071] In order to obtain the excellent antiglare property and
transparency, the particles preferably has a mean particle size of
1 to 10 .mu.m. Preferred examples of the particles are transparent
organic resin particles, particularly cross-linked acrylic resin
particles, cross-linked styrene resin particles and cross-linked
acrylic-styrene copolymer. Further, in order to ensure the
antiglare property and transparency, the mesh-shaped conductive
layer preferably has the thickness of 1 to 15 .mu.m. Furthermore,
in order to ensure the antiglare property and transparency, it is
efficient that the antiglare layer is configured to have a
transmission image sharpness established in JIS-K-7105 not less
than 150 and a reflection image sharpness (reflection angle: 45
degrees) established in JIS-K-7105 is not more than 100. In this
case, the measurement of these sharpnesses is carried out with
respect to a laminate comprising a film, a conductive layer, a
sealing layer and an anti-glare layer (FIG. 1), or a laminate
comprising a film, a conductive layer and an antiglare layer (FIG.
3).
[0072] Considering the above-mentioned points, in the present
invention, the mean height of the particles, from the surface of
the antiglare layer to the surface of the exposed particles, is
preferably in the range of 10 to 50%, particularly in the range of
10 to 40% based on the mean particles of the particles.
[0073] FIG. 2 shows that a fragmentary enlarged sectional view of
the schematic sectional view of the optical filter show in FIG. 1.
T is the thickness of the antiglare layer 14. The particles 14A
having a particle size DI (actually, mean particle size), which is
larger than the thickness of the antiglare layer, are embedded in
the antiglare layer so that the particles protrudes from the
antiglare layer by the length, D2. D2 corresponds to from 10 to 50%
(particularly, from 10 to 40%) of mean particle size D1 of the
particles.
[0074] In the present invention, the height/distance from the
surface of the abovementioned film to the surface of the antiglare
layer (the thickness of the antiglare layer (T described above))
was calculated from a difference obtained by measuring the surface
of the film and the surface of the anti-glare layer formed on the
surface of the film by using a surface roughness meter (trade name:
SURFCOM480A available from Tokyo Seimitsu Co., Ltd) in accordance
with JIS B0601-2001.
[0075] The height from the surface of the antiglare layer to the
surface of the exposed particles can be calculated from a profile
curve obtained by measuring by using the surface roughness meter
(trade name: SURFCOM480A available from Tokyo Seimitsu Co., Ltd) in
accordance with JIS B0601-2001. This was carried out at a
measurement length of 2 mm.
[0076] The surface roughness (Ra) of the antiglare layer is
preferably in the range of 0.05 to 0.6 .mu.m. The measurement is
carried out by using the surface roughness meter (trade name:
SURFCOM480A from Tokyo Seimitsu Co., Ltd) in accordance with JIS
B0601-2001.
[0077] The resin of the antiglare layer is preferably an
ultraviolet curable resin. Thereby, a hard coat function (function
of a hard coat layer) can be easily given to the antiglare layer.
Further, the sealing layer has the same composition as that of the
antiglare layer. The antiglare property can be stably obtained and
productivity is enhanced.
[0078] FIG. 3 shows a schematic sectional view (central fragmentary
view) of another embodiment of the optical filter for a display of
the present invention.
[0079] An optical filter of the present invention comprises a
transparent film 31, a mesh-shaped conductive layer
(electromagnetic wave shielding layer) 33 formed on the transparent
film 31 and an antiglare layer 34 provided on the conductive layer
33. The antiglare layer 34 contains particles 34A protruded from
the surface of the antiglare layer 34. Excellent anti-glare
property and transparency are obtained even if the filter has such
the simple structure.
It is particularly efficient when the thickness of the mesh is thin
(for example, not more than 5 .mu.m). In this embodiment, the
thickness of the anti-glare layer is preferably greater than the
thickness of the mesh of the metal conductive layer by 1 .mu.m or
more.
[0080] FIG. 4 shows a fragmentary schematic sectional view (central
fragmentary view) of a preferred embodiment of an optical filter of
the present invention. A mesh-shaped conductive layer 43, a sealing
layer 42, an antiglare layer 44 comprising particles 44A and a low
refractive index layer 45 are formed on one surface of a
transparent film 41 in this order. Further, a near-infrared
absorption layer 46 is formed on the other surface of the
transparent film 41, and a transparent adhesive layer 47 is formed
on the near-infrared absorption layer 46.
[0081] FIG. 5 shows an entire schematic sectional view of a
preferred embodiment of the optical filter of FIG. 4. A mesh-shaped
conductive layer 43, a sealing layer 42, an antiglare layer 44
comprising particles 44A and a low refractive index layer 45 are
formed on one surface of a transparent film 41 in this order.
Further, a near-infrared absorption layer 46 is formed on the other
surface of the transparent film 41, and a transparent adhesive
layer 47 is formed on the near-infrared absorption layer 46.
[0082] In this embodiment, the antiglare layer 44 has a peripheral
antiglare layer 44' at the peripheral/outer area thereof, via a
conductive layer-exposed area 43' (generally obtained by removing
each layer with a laser). The antiglare layer 45 also has a
periphery low refractive index layer 45' outside of a conductive
layer-exposed area 43' on the periphery antiglare layer 44'.
Electrical conduction can be easily obtained by using the
conductive layer-exposed area 43' when the optical filter is
attached to PDP. Further, a conductive layer-exposed area may be
formed by entirely removing the periphery antiglare layer 44' and
the periphery low refractive index layer 45'.
[0083] FIG. 6 shows a plane view of a preferred example of an
optical filter of the present invention, which a frame-shaped
conductive layer-exposed area 43' formed at the entire periphery of
the antiglare layer 44 and the low refractive index layer 45, and
the frame-shaped peripheral antiglare layer 44' and the
frame-shaped peripheral low refractive index layer 45' are formed
outside of the conductive layer-exposed area 43'.
[0084] The conductive layer-exposed area 43' is used as an
electrode part for an earth. It is preferable that the width of the
peripheral narrow zonal area ("L" in FIGS. 5 and 6'') is generally
in the range of 1 to 100 mm, particularly in the range of 2 to 50
mm. It is preferable that the width of the narrow zonal area of the
peripheral antiglare layer 44' (and the peripheral low refractive
layer 45') is generally in the range of 0.1 to 20 mm, particularly
in the range of 0.5 to 5 mm.
[0085] There is no special restriction as to the portion where the
conductive layer is exposed, as long as the portion is available as
an electrode part for an earth. It is preferable that at least of a
part of the periphery of the conductive layer is exposed. For
example, it is possible to use the portion having a configuration
of island-shaped areas, which are present intermittently in the
periphery of the conductive layer. The conductive layer can be
exposed in the island-shaped areas. The island-shaped areas may be
in any shape such as a rectangle, oval, circle or polygonal shape.
Further, the island-shaped areas may have the same or different
size from each other. As shown in FIGS. 5 and 6, it is more
preferable that the conductive layer is exposed in the form of a
belt at the periphery of the conductive layer surface.
[0086] Furthermore, the portion where the conductive layer is
exposed it is not limited to the above described configuration. It
is also possible that at least a lateral part the conductive layer
is partially exposed. With such configuration, it is possible to
use the conductive layer as an electrode part for an earth.
[0087] The antiglare layer generally has excellent antireflection
property and an antireflection layer is often unnecessary.
Accordingly, it becomes possible to free set/choose the refractive
index of the other layers, and the materials for the layers can be
widely chosen. Hence, it is possible to enjoy the cost reduction.
When both the antiglare layer and the low refractive layer are
used, highly improved antireflection property is obtained, compared
to the instance where only the antiglare layer is used.
[0088] Formation of the antiglare layer or the combination of the
sealing layer and the antiglare layer is preferably carried out by
applying a coating liquid which particles are dispersed in a resin
and an organic solvent. In this case, it is preferable that the
components of the optical filter (e.g. a mesh, a primer layer and a
substrate) are free from corrosion by use of an organic solvent,
and that high transparency can be obtained. Thus, the resultant
optical filter preferably has a haze value of not more than 10%.
The haze value is preferably determined by using Full Automatic
Direct-Reading Haze Computer (HGM-2DP; manufactured by Suga
Shikenki K.K.) according to JIS K 7105 (1981).
[0089] An example of the near-infrared absorption layer and the
transparent adhesive layer is shown in FIG. 4. Alternatively, a
near-infrared absorption layer, a neon-cut layer or a transparent
adhesive layer, or a combination of two or more of these layers may
be employed. Alternatively, an optical filter comprising a
transparent adhesive layer having near-infrared absorption function
and neon-cut function, an optical filter comprising a near-infrared
absorption layer having neon-cut function and a transparent
adhesive layer (these are provided on a transparent film in this
order) or an optical filter comprising a near-infrared absorption
layer, a neon-cut layer and transparent adhesive layer (these are
provided on a transparent film in this order) is also
preferred.
[0090] The above-mentioned conductive layer 13, 33, 43 is a
mesh-shaped metal layer or a mesh-shaped metal-containing layer.
The mesh-shaped metal layer or the mesh-shaped metal-containing
layer is generally formed by etching or the printing process, or a
metal fabric layer. Hence, a low resistivity is easily obtained.
Generally, spaces defined by the mesh-shaped metal layer or the
mesh-shaped metal-containing layer are filled by the sealing layer
12, 42, as described above. Hence, transparency and antiglare
property are enhanced.
[0091] The low refractive index layer 45 constitutes an
antireflection layer. That is to say, a composite film, which
comprising the antiglare layer and the low refractive layer formed
on the antiglare layer, effectively exhibits an antireflection
effect. A high refractive index layer may be provided between the
low refractive index layer and the antiglare layer. Hence,
antireflection function is enhanced.
[0092] It is possible to only provide the transparent film and the
antiglare layer. In this case, t the low refractive index layer 45,
etc can be omitted. The antiglare layer and the anti reflection
layer, etc. are generally formed by coating. Coating operation is
preferable in view of productivity and economy.
[0093] The abovementioned near-infrared absorption layer 46 has a
near-infrared radiation blocking function in PDP. Generally
speaking, the near-infrared absorption layer contains a pigment
having absorption maximum at 800 to 1200 nm. The transparent
adhesive layer 36 is generally provided for an easy installation to
a display. An exfoliative sheet may be provided on the transparent
adhesive layer 36.
[0094] An optical filter of the present invention is obtained, for
example by forming a mesh-shaped metal conductive layer on the
entire surface of a rectangle transparent film, and then forming an
antiglare layer on the entire area of the mesh-shaped metal
conductive layer. If desired, a near-infrared absorption layer is
provided on the back surface of the transparent film, and a
transparent adhesive layer is provided on the near-infrared
absorption layer. Thereafter, if desired, electrode parts may be
formed at four edges of entire circumference of the antiglare layer
by irradiating a laser to the periphery of the layer.
[0095] The above embodiment was an optical filter for a display
comprising a single transparent film. Alternatively, two
transparent films may be used in the optical filter of the
invention. The optical filter can be obtained by the following
process:
[0096] Namely, a mesh-shaped conductive layer is provided on a
first trans-parent film (which in general has a near-infrared
absorption layer or the like on the back side). A second
transparent film is provided, which has an antiglare layer and an
antireflection layer such as a low refractive index layer on the
second transparent film. On the conductive layer provided on the
first transparent film, the second transparent film is laminated by
the application, if necessary, of an adhesive layer provided at the
back side of the second transparent film. A laser is irradiated on
the antireflection layer such as the antiglare layer and the low
refractive layer, if necessary.
[0097] Alternatively, a mesh-shaped metal conductive layer, an
antiglare layer and an antireflection layer such as a low
refractive layer are provided on a surface of a transparent film in
this order, and a near-infrared absorption layer is provided on a
surface of another transparent film and a trans-parent adhesive
layer is provided on the near-infrared absorption. Then, the
surfaces of two transparent films, where no layers are provided,
are bonded with each other. The former laminate can be prepared by
a process of the present invention.
[0098] The two transparent films are employed when it is favorable
for the manufacture. However, it could be disadvantageous to use
two transparent films because of bulkiness or the increase of
thickness.
[0099] Materials used in the optical filter for a display of the
present invention are explained below.
[0100] The film is generally a transparent film, particularly a
transparent plastic film. The materials may be anything having
transparency (the transparency meaning transparency to visible
light). Examples of the material of the plastic film include
polyester such as polyethylene terephthalate (PET) and polybutylene
terephthalate, acrylic resin such as polymethyl methacrylate
(PMMA), polycarbonate (PC), polystyrene, cellulose triacetate,
polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride,
polyethylene, ethylene-vinyl acetate copolymer, polyvinyl butyral,
metal-crosslinked ethylene-methacrylic acid copolymer, polyurethane
and cellophane. Preferred are polyethylene terephthalate (PET),
polycarbonate (PC), polymethyl methacrylate (PMMA), because have
high resistance to processing load such as heat, solvent and
bending and high transparency. Especially PET is preferred because
of excellent processing properties.
[0101] The transparent film has generally a thickness of 1 .mu.m to
10 mm, preferably 1 .mu.m to 5 mm, particularly 25 to 250 .mu.m
depending upon the application of the optical filter.
[0102] A surface resistance value of the metal conductive layer
according to the invention is generally not more than
10.OMEGA./.quadrature., preferably in the range of 0.001 to
5.OMEGA./.quadrature., especially in the range of 0.005 to
5.OMEGA./.quadrature..
[0103] Examples of the mesh-shaped (lattice-shaped) conductive
layer include a layer obtained by fabricating a metal e.g., a metal
fiber and an organic fiber coated with metal into a net shape, a
layer obtained by etching a metal (e.g., Cu) layer provided on a
transparent film so as to form a mesh having openings, and a layer
obtained by printing an electrically conductive ink on a
transparent film so as to form a mesh.
[0104] It is preferable that the mesh of the mesh-shaped metal
conductive layer is comprises the metal fiber and/or the organic
fiber coated with metal. It is preferable that the mesh has line
width of 1 .mu.m to 1 mm and opening ratio of 40 to 95%. Further
preferred is a mesh having line width of 10 to 500 .mu.m and
opening ratio of 50 to 95%. When the mesh-shaped conductive layer
has a line width more than 1 mm, the electromagnetic wave shielding
property is improved, but the opening ratio is decreased. Namely,
both the excellent shielding property and opening ratio cannot be
obtained. On the other hand, the line width less than 1 .mu.m
brings about a mesh with a poor strength that is difficult to
handle. Moreover, the conductive layer with an opening ratio of
more than 95% is difficult to maintain the shape as a mesh. When
the conductive layer has an opening ratio of less than 40%, the
optical transparency is decreased, and the light amount from a
display is decreased.
[0105] The opening ratio (aperture ratio) of the mesh-shaped
conductive layer means the proportion of the area of the opening
portion to the projected area in the layer.
[0106] As the metal of the metal fiber and the organic fiber coated
with metal constituting the mesh-shaped conductive layer, copper,
stainless steel, aluminum, nickel, titanium, tungsten, tin, lead,
iron, silver, carbon or an alloy thereof, preferably copper,
stainless, or nickel can be used.
[0107] As organic materials of the organic fiber coated with metal,
polyester, nylon, vinylidene chloride, aramid, vinylon, or
cellulose can be used.
[0108] In a patternwise etched conductive foil such as metallic
foil, as metals for the metallic foil, copper, stainless steel,
aluminum, nickel, iron, brass or alloys thereof, preferably copper,
stainless steel or aluminum can be used.
[0109] When the thickness of the metal foil is excessively small,
the handling property of the foil and the workability of pattern
etching are reduced. On the other hand, when the thickness of the
metal foil is excessively large, the thickness of the resultant
filter is increased and the time required for etching procedure is
lengthened. Therefore, the thickness of the conductive layer
preferably is in the range of 1 to 200 .mu.m.
[0110] The etched pattern may have any shapes. For example, the
metallic foil is in the form of a lattice, which is obtained by
forming square openings (pores) in a foil, or in the form of a
punching metal, which is obtained by forming circle, hexagon,
triangle or ellipse openings in a foil. The openings may be
regularly arranged or irregularly arranged to have a random
pattern. The opening ratio (the proportion of the area of the
opening portion to the projected area) of the metal foil is
preferably in the range of 20 to 95%. The line width of 1 .mu.m to
1 mm and the opening ratio of 40 to 50% are preferred. The line
width of 10 to 500 .mu.m and opening ratio of 50 to 95% are more
preferred.
[0111] In addition to the above mesh-shaped conductive layer, a
mesh-conductive layer can be used. The conductive layer can be
obtained by forming dots on a film by using a material soluble in a
solvent, and forming a conductive materials layer on the film, the
conductive layer including a conductive material insoluble in the
solvent. In this way, the film is brought into contact with the
solvent, and then the dots and the conductive materials on the dots
are removed, to prepare the mesh-shaped conductive layer.
[0112] An anchor coat layer may be formed on the surface on which
the metal conductive layer is formed. By using the anchor coat
layer, the adhesion property between the film and the metal
conductive layer can be enhanced. Dots can be formed in high print
precision.
[0113] The anchor coat layer includes at least a synthetic resin.
As the synthetic resin, polyester resin, polyurethane resin,
acrylic resin and vinyl acetate resin can be used.
[0114] Further, the anchor coat layer preferably includes a
silicone oil and a synthetic resin. Such anchor coat layer is
formed, for example by applying a coating liquid comprising
silicone oil and synthetic resin to the film, with a roll coater.
The anchor coat is prepared after being cured by heating.
[0115] As examples of silicone oils, dimethyl silicone oil, methyl
phenyl silicone oil, methyl hydrogen silicone oil, polyether
modified silicone oil, alkyl modified silicone oil, amino modified
silicone oil, and epoxy modified silicone oil are used. The content
of the silicone oil in the anchor coat layer is preferably in the
range of 0.0005 to 5% by weight, particularly in the range of
0.0005 to 0.5% by weight.
[0116] Further, the anchor coat layer is more preferably a hardened
layer prepared from a composition comprising a synthetic resin
having a group having active hydrogen and polyisocyanate having at
least two isocyanate groups. Based on the composition, the
resistant to solvents can be enhanced.
[0117] Examples of the group having active hydrogen include
hydroxyl group, primary amino group, secondary amino group and
carboxyl group, and preferably hydroxyl group. The equivalent
amount of the group having the active hydrogen (e.g. the hydroxyl
number) is preferably in the range of 10 to 300 mgKOH/g,
particularly in the range of 30 to 100 mgKOH/g, based on the resin
(1 g).
[0118] Examples of the polyisocyanate include aromatic isocyanate
such as tolylene diisocyanate (TDI), isophorone diisocyanate,
xylylene diisocyanate, diphenylmethane-4,4-diisocyanate;
dicyclopentanyl diisocyanate, hexamethylene diisocyanate,
2,4,4'-trimethylhexamethylene diisocyanate,
2,2',4-trimethylhexamethylene diisocyanate. Polyisocyanate based on
an isocyanate compound having functionality of 3 or more such as
TDI adduct of trimethylolpropane can be also used. Aromatic
polyisocyanate is preferred in these polyisocyanate.
[0119] A metal plated (metallic deposit) layer may be further
provided on the metal conductive layer in order to enhance
conductive property (particularly, in case of a method wherein dots
are formed by using materials soluble in the abovementioned
solvents). The plated layer can be formed by conventional
electrolytic plating and nonelectrolytic plating. Examples of the
metals used in the plating generally include copper, copper alloy,
nickel, aluminum, silver, gold, zinc and tin. Preferred is copper,
copper alloy, silver or nickel. Particularly, copper or copper
alloy is preferred in view of economic efficiency and conductive
property.
[0120] Further, antiglare property can be imparted to the
conductive layer. For the antiglare treatment, a blackened
treatment may be carried out on a surface of the (mesh-shaped)
conductive layer. For example, oxidation treatment of metal layer,
black plating of chromium alloy, or application of black or dark
color ink can be carried out.
[0121] The antiglare layer is a layer comprising, as a main
component, a synthetic resin and particles. Examples of the
synthetic resin are acrylic resin layer, epoxy resin layer,
urethane resin layer, silicone resin layer. the thickness is
generally in the range of 0.01 to 20 .mu.m, preferably in the range
of 1 to 10 .mu.m. A portion of the particle is protruded from the
surface of the layer. The synthetic resin is, in general, a
thermosetting resin or ultraviolet curable resin, and preferably
ultraviolet curable resin. Since the ultraviolet curable resin can
be cured in a short time, has excellent productivity and is easily
removed by a laser, the ultraviolet curable resin is preferably
used.
[0122] Examples of the thermosetting resin include phenol resin,
resorcinol resin, urea resin, melamine resin, epoxy resin, acrylic
resin, urethane resin, furan resin and silicon resin.
[0123] The antiglare layer is preferably a hardening layer
comprising, as a main component, an ultraviolet curable resin
composition (comprising ultraviolet curable resin,
photopolymerization initiator, and etc.)
[0124] Examples of the ultraviolet curable resins (monomers,
oligomers) include (meth)acrylate monomers such as 2-hydroxyethyl
(meth)acrylate, 2-hydroxyropyl (meth)acrylate, 4-hydroxybutyl
(meth)acrylate, 2-ethylhexylpolyethoxy (meth)acrylate, benzyl
(meth)acrylate, isobornyl (meth)acrylate, phenyloxyethyl
(meth)acrylate, tricyclodecane mono(meth)acrylate,
dicyclopentenyloxyethyl (meth)acrylate, tetrahydrofurfuryl
(meth)acrylate, acryloylmorpholine, N-vinylcaprolactam,
2-hydroxy-3-phenyloxypropyl (meth)acrylate, o-phenylphenyloxyethyl
(meth)acrylate, neopentylglycol di(meth)acrylate, neopentyl glycol
dipropoxy di(meth)acrylate, neopentyl glycol hydroxypivalate
di(meth)acrylate, tricyclodecanedimethylol di(meth)acrylate,
1,6-hexanediol di(meth)acrylate, nonanediol di(meth)acrylate,
trimethylolpropane tri(meth)acrylate, pentaerythritol
tri(meth)acrylate, pentaerythritol tetra(meth)acrylate,
tris[(meth)acryloxyethyl]isocyanurate and ditrimethylolpropane
tetra(meth)acrylate; and
[0125] the following (meth)acrylate oligomer such as:
[0126] polyurethane (meth)acrylate such as compounds obtained by
reaction among the following polyol compound and the following
organic polyisocyanate compound and the following
hydroxyl-containing (meth)acrylate:
[0127] the polyol compound (e.g., polyol such as ethylene glycol,
propylene glycol, neopentyl glycol, 1,6-hexanediol,
3-methyl-1,5-pentanediol, 1,9-nonanediol,
2-ethyl-2-butyl-1,3-propanediol, trimethylolpropane, diethylene
glycol, dipropylene glycol, polypropylene glycol,
1,4-dimethylolcyclohexane, bisphenol-A polyethoxydiol and
polytetramethylene glycol; polyesterpolyol obtained by reaction of
the above-mentioned polyol with polybasic acid or anhydride thereof
such as succinic acid, maleic acid, itaconic acid, adipic acid,
hydrogenated dimer acid, phthalic acid, isophthalic acid and
terephthalic acid; polycaprolactone polyol obtained by reaction of
the above-mentioned polyol with .epsilon.-caprolactone; a compound
obtained by reaction of the above-mentioned polyol and a reaction
product of the above-mentioned polybasic acid or anhydride thereof
and .epsilon.-caprolactone; polycarbonate polyol; or polymer
polyol), and
[0128] the organic polyisocyanate compound (e.g., tolylene
diisocyanate, isophorone diisocyanate, xylylene diisocyanate,
diphenylmethane-4,4'-diisocyanate, dicyclopentanyl diisocyanate,
hexamethylene diisocyanate, 2,4,4'-trimethylhexamethylene
diisocyanate, 2,2',4-trimethylhexamethylene diisocyanate), and
[0129] the hydroxyl-containing (meth)acrylate (e.g., 2-hydroxyethyl
(meth)acrylate, 2-hydroxyropyl (meth)acrylate, 4-hydroxybutyl
(meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate,
cyclohexane-1,4-dimethylolmono(meth)acrylate, pentaerythritol
tri(meth)acrylate or glycerol di(meth)acrylate);
[0130] bisphenol-type epoxy(meth)acrylate obtained by reaction of
bisphenol-A epoxy resin or bisphenol-F epoxy resin and
(meth)acrylic acid.
[0131] These compounds can be employed singly or in combination of
two or more kinds. The ultraviolet curable resin may be used
together with thermo polymerization initiator, i.e., these can be
employed as a thermosetting resin.
[0132] In the abovementioned ultraviolet curable resin, rigid
polyfunctional monomer such as pentaerythritol tri(meth)acrylate,
pentaerythritol penta(meth)acrylate, or dipentaerythritol
hexa(meth)acrylate is preferably used as a main component, in order
to give a hard coat function to the anti-glare layer.
[0133] Photopolymerization initiators of the ultraviolet curable
resin can be optionally selected depending upon the properties of
the ultraviolet curable resin used. Examples of the
photopolymerization initiators include acetophenone type initiators
such as 2-hydroxy-2-methyl-1-phenylpropane-1-on,
1-hydroxycyclohexylphenylketone and
2-methyl-1-[4-(methylthio)phenyl]-2-morphorino-propane-1-on;
benzoin type initiators such as benzylmethylketal; benzophenone
type initiators such as benzophenone, 4-phenylbenzophenone and
hydroxybenzophenone; thioxanthone type initiators such as
isopropylthioxanthone and 2,4-diethylhioxanthone. Further, as
special type, there can be mentioned methylphenylglyoxylate.
Especially preferred are 2-hydroxy-2-methyl-1-phenylpropane-1-on,
1-hydroxycyclohexylphenylketone,
2-methyl-1-[4-(methylthio)phenyl]-2-morphorinopropane-1-on and
benzophenone. These photopolymerization initiators can be employed
together with one or more kinds of a conventional
photopolymerization promoter such as a benzoic acid type compound
(e.g., 4-dimethylaminobenzoic acid) or a tertiary amine compound by
mixing with the promoter in optional ratio. Only the initiator can
be employed singly or in combination of two or more kinds.
Especially, 1-hydroxycyclohexylphenylketone (Irgercure 184,
available from Chiba-Specialty Chemicals) is preferred.
[0134] The initiator is preferably contained in the range of 0.1 to
10% by weight, particularly 0.1 to 5% by weight based on the resin
composition.
[0135] The antiglare layer of the present invention contains
particles as described above. The particles may be inorganic
particles or organic resin particles. The organic particles are
preferred from the standpoint of excellent transparency. Examples
of the organic resin particles include cross-linked acrylic resin
particles, cross-linked styrene resin particles and cross-linked
acrylic-styrene copolymer particles. Examples of the inorganic
particles include ITO, TiO.sub.2, ZrO.sub.2, CeO.sub.2, SiO.sub.2,
Al.sub.2O.sub.3, Y.sub.2O.sub.3, La.sub.2O.sub.3, LaO and
Ho.sub.2O.sub.3. These can be employed singly or in combination of
two or more kinds. The fine particles preferably have mean particle
size of 1 to 10 .mu.m. When the mean particle size is less than 1
.mu.m, sufficient anti-glare effect cannot be obtained because the
protrusion of the particles from the antiglare layer is small. When
the mean particle size is more than 10 .mu.m, it is not preferred,
because the visibility can be largely decreased. The amount of the
particles is generally in the range of 0.1 to 10% by weight,
preferably in the range of 0.1 to 5% by weight based on the resin
composition for forming the antiglare layer.
[0136] In the antiglare layer, it is preferable that there is
substantially no difference between the refractive index of the
resin in which the particles are dispersed and that of the
particles. Thereby, the light scattering at an interface between
the resin and the particles can be inhibited. Accordingly,
transparency of the antiglare layer can be enhanced. The difference
between the refractive index of the resin and that of the particles
in the antiglare layer is preferably not more than 0.03,
particularly not more than 0.02.
[0137] The refractive index of the resin can be determined, for
instance, by using Abbe refractometer (Trade name: DR-M2/1550)
available from Atago, Co., Ltd. More precisely, the refractive
index of the particles is determined by using solvents. In other
words, two solvents having different refractive indexes from each
other are mixed at different mixing ratios. The particles are
dispersed in the mixed solvents in equal amounts, to obtain
dispersions. A dispersion having the smallest turbidity is chosen,
and the refractive index of the dispersion is measured by the Abbe
refractometer. Thus, the refractive index of the particles is
determined.
[0138] Further, the antiglare layer may contain a small amount of
ultraviolet absorber, infrared absorber, anti-aging agent, paint
processing auxiliary agent, colorant, or the like. It is
particularly preferable that the antiglare layer contains the
ultraviolet absorber (e.g. benzotriazol ultraviolet absorber or
benzophenone ultraviolet absorber). By including the ultraviolet
absorber, the filter can be efficiently prevented from yellowing or
the like. The amount of the ultraviolet absorber is generally in
the range of 0.1 to 10% by weight, preferably in the range of 0.1
to 5% by weight based on the resin composition.
[0139] The sealing layer 12, 32 formed under the antiglare layer
may be the same layer as the antiglare layer or may be a layer
comprising the resin used in the antiglare layer (which does not
contain particles). When the composition of the sealing layer is
the same as that of the antiglare layer except for the particles,
the composition can be easily prepared and productivity is
enhanced. This is because the identical composition can be used for
forming these layers, except for adding the particles to one of
these layers.
[0140] The thickness of the sealing layer corresponds to the
thickness of the mesh, for filling the spaces of the mesh-shaped
conductive layer.
[0141] The high refractive index layer is preferably a layer (cured
layer) in which conductive metal oxide particles (inorganic
compound) such as ITO, ATO, Sb.sub.2O.sub.3, SbO.sub.2,
In.sub.2O.sub.3, SnO.sub.2, ZnO, Al-doped ZnO, TiO.sub.2 are
dispersed in a polymer (preferably ultraviolet curable resin). The
conductive metal oxide particle generally has mean particle size of
10 to 10,000 nm, preferably 10 to 50 nm. Especially, ITO
(especially mean particle size of 10 to 50 nm) is preferred. The
high reflective index layer preferably has refractive index of not
less than 1.64. The thickness generally is in the range of 10 to
500 nm, preferably 20 to 200 nm.
[0142] In the case where the high refractive index layer is a
conductive layer, the minimum reflectivity at the surface of the
antireflection layer can be reduced to 1.5% or less by increasing
the refractive index of the high reflective index layer to 1.64 or
more. Further, the minimum reflectivity at the surface of the
antireflection layer can be reduced to 1.0% or less by increasing
the reflective index of the high reflective index layer to 1.69 or
more, preferably a value in the range of 1.69 to 1.82.
[0143] The low refractive index layer preferably is a layer (cured
layer) in which particles of silica or fluorine resin (preferably
hollow silica) are dispersed in a polymer (preferably ultraviolet
curable resin). The low refractive index layer contains preferably
10 to 40% by weight, especially 10 to 30% by weight of the
particles. The low refractive index layer preferably has refractive
index of 1.40 to 1.51. The refractive index of more than 1.51
brings about reduction of antireflection property of the
antireflection film. The thickness of the low refractive index
layer is, in general, in the range of 10 to 500 nm, preferably in
the range of 20 to 200 nm.
[0144] The hollow silica preferably has mean particle size of 10 to
100 nm, preferably 10 to 50 nm, and specific gravity of 0.5 to 1.0,
especially 0.8 to 0.9.
[0145] To form each layer (antiglare layer, sealing layer or
antireflection layer), as described above, the abovementioned
particles can be mixed with a resin (preferably ultraviolet curable
resin) if necessary. The resultant coating liquid is applied to the
surface of the conductive layer formed on the transparent film.
Thereafter, the coating liquid is dried and subsequently cured by
UV irradiation. In this case, each layer may be formed by coating
and cured one by one. Alternatively, all the layers can be
successively formed by coating, and then all the layers can be
cured entirely.
[0146] The formation of the layers is carried out by
applying/coating a coating liquid (solution) to a conductive layer
or the like. The coating liquid, e.g., a solution comprising an
ultraviolet curable resin such as an acrylic monomer in a solvent
such as toluene, is applied to the conductive layer or the like, by
means of gravure coater. Thereafter, the coated layer is dried, and
then cured by exposure to UV rays. This wet-coating method enables
high-speed, uniform and cheap film formation. After the coating,
for example, the coated layers are exposed to UV rays to be cured,
whereby the effects such as improved adhesion and enhanced hardness
of the layer can be obtained.
[0147] In the UV-rays curing, it is possible to adopt, as light
source used, various sources generating light in the wavelength
range of ultraviolet to visible rays. Examples of the source
include super-high-pressure, high-pressure and low-pressure mercury
lamps, a chemical lamp, a xenon lamp, a halogen lamp, a mercury
halogen lamp, a carbon arc lamp, and an incandescent electric lamp,
and laser beam. The exposing time is generally in the range of a
few seconds to a few minutes, depending upon kinds of lamp and
strength of light. To promote the curing, the laminate may be
heated beforehand to a temperature in the range of 40 to
120.degree. C., and then the heated laminate may be exposed to
ultraviolet rays.
[0148] The near-infrared absorption layer is generally obtained by
forming a layer containing a dye on a surface of the transparent
film. The near-infrared absorption layer is prepared by applying a
coating liquid, which comprises an ultraviolet- or
electron-beam-curable resin or thermosetting resin, and the dye and
binder resin, to a conductive layer or the like. The layer is
completed, if desired, by drying and curing the layer.
Alternatively, it is possible to prepare the absorption layer from
the coating liquid comprising the dye, binder resin and the like,
followed only by drying. When the near-infrared absorption layer is
used as a film, it is generally a near-infrared cut film, such as
dye-containing film. The dye generally has absorption maximum in
wavelength of 800 to 1200 nm. Examples of the dye include
phthalocyanine dyes, metal complexes dyes, nickel dithioren
complexes dyes, cyanine dyes, squalirium dyes, polymethine dyes,
azomethine dyes, azo dyes, polyazo dyes, diimmonium dyes, aminium
dyes, anthraquinone dyes. Preferred are cyanine dyes,
phthalocyanine dyes and diimmonium dyes. These dyes can be employed
singly or in combination. Examples of the binder resin include
thermoplastic resin such as acrylic resin.
[0149] In the invention, a neon-emission absorption function may be
given to the near-infrared absorption layer such that the
near-infrared absorption layer has function for adjusting color
hue. For this purpose, a neon-emission absorption layer may be
provided, or a neon-emission selective absorption dye is added to
the near-infrared absorption layer.
[0150] Examples of the neon-emission selective absorption dyes
include cyanine dyes, squalirium dyes, anthraquinone dyes,
phthalocyanine dyes, polymethine dyes, polyazo dyes, azulenium
dyes, diphenylmethane dyes, triphenylmethane dyes. The
neon-emission selective absorption dyes are required to have
neon-emission selective absorption function at wavelength of
approx. 585 nm. It is also necessary for the neon-emission
selective absorption dyes to have a small absorption in the visible
light wavelength range except for the above-mentioned wavelength.
Hence, the dyes preferably have absorption maximum wavelength of
575 to 595 nm having spectrum half bandwidth of 40 nm or less.
[0151] It is possible to use a plurality of absorption dyes
including dyes for absorbing near-infrared light and dyes for
absorbing neon emission light are used in combination. In that
case, it is not necessary for all the absorption dyes to be
contained in the same layer, and the absorption dyes can be added
to different layers. Such separate addition can be considered,
especially when the dyes have insufficient solubilities, the mixed
dyes react with each other, or the thermal resistance or moisture
resistance of the layer is deteriorated by the mixed
application.
[0152] Further, coloring materials, ultraviolet absorbers, and
antioxidants may be added unless these materials adversely affect
the optical properties of the filter.
[0153] As to the near-infrared absorption properties of the optical
filter of the invention, the transmittance of light in a wavelength
range of 850 to 1000 nm preferably is 20% or lower, more preferably
15% or lower. As to the selective absorption properties of the
optical filter, the transmittance of light at a wavelength of 585
nm preferably is 50% or lower. The former is effective for reducing
the transmittance of a light in the wavelength range, which is
considered to cause malfunction of remote control systems in
peripheral devices. In the latter case, it is effective to absorb
orange light having a peak wavelength in the range of 575 to 595
nm, which affects to the deterioration of color reproductively.
Accordingly, red light is rendered more intrinsic, and the
reproducibility of colors is improved.
[0154] The near-infrared absorption layer generally has thickness
of 0.5 to 50 .mu.m.
[0155] When the conductive adhesive tape is attached to the
conductive layer having an exposed periphery, a material including
an adhesive layer on one surface of a metal foil can be used as the
conductive adhesive tape. In the adhesive layer, conductive
particles are included in a dispersed state. For the adhesive
layer, acrylic adhesive, rubber adhesive or silicon adhesive, or an
epoxy or phenol resin adhesive including a curing agent can be
used.
[0156] Various particles can be used as the conductive particles to
be dispersed in the adhesive layer, as long as the particles are
excellent electrical conductors. For examples, powder of metal such
as copper, silver or nickel, and resin powder or ceramic powder
coated with these metals can be used. Further, there is no
limitation in shape, and any shape such as bulb, dendriform, grain
and pellet can be employed.
[0157] The amount of the conductive particles is preferably in the
range of 0.1 to 15% by volume based on the polymer constituting the
adhesive layer, and the mean particle size is preferably in the
range of 0.1 to 100 .mu.m. Concentration/aggregation of the
conductive particles is prevented and excellent conductivity can be
obtained by the above-prescribed amount and the particle size.
[0158] As the metal foil for forming a substrate of the conductive
adhesive tape, copper, silver, nickel, aluminum and stainless steel
can be used. The thickness of the foil is usually in the range of 1
to 100 .mu.m.
[0159] The adhesive layer can be easily formed by applying the
above adhesive which is uniformity mixed with the conductive
particles at a predetermined ratio to the metal foil by a roll
coater, a die coater, a knife coater, a micabar coater, a flow
coater, a spray coater, or the like.
[0160] The adhesive layer generally has the thickness of 5 to 100
.mu.m.
[0161] In stead of the conductive adhesive tape, an adhesive agent
made of the above material for the adhesive layer may be coated to
the exposed area of the conductive layer, and the above-mentioned
conductive tape may be further attached thereto.
[0162] The transparent adhesive layer of the invention is used for
bonding the optical filter of the invention to a display, and
therefore any resin having adhesion function can be used as
materials for forming the adhesive layer. Examples of the material
include acrylic adhesives made of butyl acrylate and the like,
rubber adhesives, TPE (thermoplastic elastomer) adhesives
comprising as a main component TPE such as SEBS
(styrene/ethylene/butylene/styrene) and SBS
(styrene/butadiene/styrene).
[0163] The thickness of the transparent adhesive layer is generally
in the range of 5 to 500 .mu.m, preferably in the range of 10 to
100 .mu.m. The optical filter can be generally bonded to a glass
plate of a display through the adhesive layer under application of
pressure thereto.
[0164] In case of using two transparent films in the invention,
examples of materials (adhesives) used in the adhesion of the films
include ethylene/vinyl acetate copolymer, ethylene/methyl acrylate
copolymer, acrylic resin (e.g., ethylene/(meth)acrylic acid
copolymer, ethylene/ethyl (meth)acrylate copolymer, ethylene/methyl
(meth)acrylate copolymer, metal-ion crosslinked
ethylene/(meth)acrylic acid copolymer), and ethylene copolymers
such as partially saponified ethylene/vinyl acetate copolymer,
carboxylated ethylene/vinyl acetate copolymer,
ethylene/(meth)acrylic acid/maleic anhydride copolymer,
ethylene/vinyl acetate/(meth)acrylate copolymer. The (meth)acrylic
acid means acrylic acid and methacrylic acid and the (meth)acrylate
means acrylate and meth acrylate. Besides these polymers, there can
be mentioned polyvinyl butyral (PVB) resin, epoxy resin, phenol
resin, silicon resin, polyester resin, urethane resin, rubber
adhesives, thermoplastic elastomer (TPE) such as SEBS
(styrene/ethylene/butylene/styrene) and SBS
(styrene/butadiene/styrene). The acrylic adhesives and epoxy resins
are preferred because they show excellent adhesion.
[0165] The thickness of the above-mentioned adhesive layer
generally is in the range of 10 to 50 .mu.m, preferably in the
range of 20 to 30 .mu.m. The optical filter can be generally
attached to a glass plate of a display through the adhesive layer
by application of pressure and heat thereto.
[0166] In the case where EVA (ethylene/vinyl acetate/ethylene
copolymer) is used as materials of the transparent adhesive layer,
EVA generally has the content of vinyl acetate in the range of 5 to
50% by weight, especially 15 to 40% by weight. When the content is
less than 5% by weight, the layer does not show satisfactory
transparency. On the other hand, when the content is more than 40%
by weight, the mechanical strength of the layer is extremely
decreased, the film formation is made difficult, and the blocking
between films readily occurs.
[0167] As a crosslinking agent for thermo crosslinking, an organic
peroxide is generally suitable. The organic peroxide is selected in
the consideration of sheet-processing temperature,
crosslinking/curing (bonding) temperature, and storage stability.
Examples of the organic peroxide include
2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethyl-2,5-(t-butylperoxy)hexyne-3, di-t-butylperoxide,
t-butylcumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane,
dicumyl peroxide,
.alpha.,.alpha.'-bis(t-butylperoxyisopropyl)benzene,
n-butyl-4,4-bis(t-butylperoxy)valerate,
2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane,
1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,
t-butylperoxybenzoate, benzoyl peroxide, t-butylperoxyacetate,
2,5-dimethylhexyl-2,5-bis(t-butylperoxy)hexyne-3,1,1-bis(t-butylperoxy)-3-
,3,5-trimethylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane,
methyl ethyl ketone peroxide,
2,5-dimethylhexyl-2,5-bisperoxybenzoate, t-butylhydroperoxide,
p-menthane hydroperoxide, p-chlorobenzoyl peroxide,
t-butylperoxyisobutylate, hydroxyheptyl peroxide and chlorohexanone
peroxide. The organic peroxide can be used singly, or in
combination of two or more kinds. The content of the organic
peroxide is generally used in an amount of not more than 5 parts by
weigh, preferably 0.5 to 5.0 parts by weight based on 100 parts by
weight of EVA.
[0168] The organic peroxide is generally kneaded with EVA by means
of an extruder or a roll mill. Alternatively, the organic peroxide
may be solved in an organic solvent, plasticizer, vinyl monomer and
the thus obtained solution may be added to an EVA film by means of
impregnation method.
[0169] The EVA may contain acryloyl group-containing compounds,
methacryloyl group-containing compounds, allyl group-containing
compounds for improvement of various properties of EVA (e.g.,
mechanical strength, optical characteristics, adhesive property,
weather resistance, whitening resistance, rate of
crosslinking).
[0170] Typical examples of the acryloyl and methacryloyl
group-containing compounds include derivatives of acrylic acid or
methacrylic acid, such as esters and amides of acrylic acid or
methacrylic acid. Examples of the ester residue include linear
alkyl groups (e.g., methyl, ethyl, dodecyl, stearyl and lauryl), a
cyclohexyl group, a tetrahydrofurfuryl group, an aminoethyl group,
a 2-hydroxyethyl group, a 3-hydroxypropyl group, and
3-chloro-2-hydroxypropyl group. Further, the esters include esters
of acrylic acid or methacrylic acid with polyhydric alcohol such as
ethylene glycol, triethylene glycol, polypropylene glycol,
polyethylene glycol, trimethylol propane or pentaerythritol.
Representative example of the amide is diacetone acrylamide.
[0171] Examples of the esters include polyfunctional esters of
acrylic acids or methacrylic acids with polyhydric alcohol such as
glycerol, trimethylol propane or pentaerythritol; and further allyl
group-containing compounds such as triallyl cyanurate, triallyl
isocyanurate, diallyl phthalate, diallyl isophthalate and diallyl
maleate. The compounds can be used singly, or in combination of two
or more kinds. The content of the compound is generally used in an
amount of 0.1 to 2 parts by weight, preferably 0.5 to 5 parts by
weight based on 100 parts by weight of EVA.
[0172] In case EVA is cured by light, sensitizer (photoinitiator)
is used instead of the organic peroxide, and it is generally used
in an amount of not more than 5 parts by weight, preferably 0.1 to
3.0 parts by weight based on 100 parts by weight of EVA.
[0173] Examples of the sensitizer include benzoin, benzophenone,
benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether,
benzoin isobutyl ether, dibenzyl, 5-nitroacenaphtene,
hexachlorocyclopentadiene, p-nitrodiphenyl, p-nitroaniline,
2,4,6-trinitroaniline, 1,2-benzanthraquinone,
3-methyl-1,3-diaza-1,9-benzanthrone. The photoinitiators can be
used singly, or in combination of two or more kinds.
[0174] In the invention, a silane coupling agent may be used to
accelerate adhesion. Examples of the silane coupling agent include
vinylethoxysilane, vinyltris(.beta.-methoxyethoxy)silane,
.gamma.-(methacryloxypropyl)trimethoxysilane,
vinyltriacetoxysilane, .gamma.-glycidoxypropyltrimethoxysilane,
.gamma.-glycidoxypropyltriethoxysilane,
.beta.-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
.gamma.-chloropropylmethoxysilane, vinyltrichlorosilane,
.gamma.-mercaptopropylmethoxysilane,
.gamma.-aminopropyltriethoxysilane,
N-.beta.-(aminoethyl)-.gamma.-aminopropyltrimethoxysilane.
[0175] The silane coupling agent can be used singly, or in
combination of two or more kinds. The content of the silane
coupling agent is generally in an amount of 0.001 to 10 parts by
weight, preferably 0.001 to 5 parts by weight based on 100 parts by
weight of EVA.
[0176] The EVA adhesive layer of the invention can further contain
a small amount of ultraviolet absorbing agent, infrared absorbing
agent, age stabilizer (antioxidant), paint processing aid and
colorant. If appropriate, filler such as carbon black, hydrophobic
silica or calcium carbonate may be contained.
[0177] The adhesive layer for adhesion can be obtained, for
example, by mixing EVA with the above-mentioned additives and
kneaded by means of extruder or roll, and then forming the sheet
having a predetermined shape by film formation method using
calendar, roll, T-die extrusion or blowing.
[0178] A protective layer may be provided on the antireflection
layer. The protective layer is preferably formed in the same manner
as in the hard coat layer.
[0179] Materials for the release sheet provided on the transparent
adhesive layer are generally transparent polymers having glass
transition temperature of not less than 50.degree. C. Examples of
the materials include polyester resin (e.g., polyethylene
terephthalate, polycyclohexylene terephthalate, polyethylene
naphthalate), polyamide resin (e.g., nylon 46, modified nylon 6T,
nylon MXD6, polyphthalamide), ketone resin (e.g., polyphenylene
sulfide, polythioether sulfone), sulfone resin (e.g., polysulfone,
polyether sulfone), polyether nitrile, polyarylate, polyether
imide, polyamideimide, polycarbonate, polymethyl methacrylate,
triacetylcellulose, polystyrene or polyvinyl chloride. Of these
resins, polycarbonate, polymethyl methacrylate, polyvinyl chloride,
polystyrene and polyethylene terephthalate can be preferably
employed. The thickness is generally in the range of 10 to 200
.mu.m, especially in the range of 30 to 100 .mu.m.
[0180] FIG. 7 shows an embodiment where an optical filter of the
present invention is attached to image-displaying surface of a
plasma display panel, that is a kind of display. An optical filter
is attached to a display surface of a display panel 70. That is to
say, an optical filter is provided on a display surface of the
display panel 70, the optical filter having a mesh-shaped
conductive layer 73, a sealing layer 72, an antiglare layer 74 and
an antireflection layer 75 such as a low refractive index layer are
formed on one surface of a transparent film 71 in this order. In
this embodiment, a near-infrared absorption layer 76 and a
transparent adhesive layer 77 are formed on the other surface of
the transparent film 71. The mesh-shaped conductive layer 73' is
exposed at periphery (marginal parts) of the filter. The exposed
mesh-shaped layer 73' and a metal cover 79 provided on the
periphery of the plasma display panel 70 are in a contact state
with each other via shield fingers (metal members in the form of
leaf springs) 78. Instead of the shield fingers, conductive gaskets
or the like may be used. Thereby, the electric conduction between
the optical filter and the metal cover 79 are conducted, and
earth/ground is performed. The metal cover 79 may be a metal frame.
As is obvious from FIG. 7, the mesh-shaped conductive layer 73 is
directed toward the viewer's side. The metal cover 79 covers the
area of about 2 to 20 mm from the periphery of the conductive layer
73. Further, the shape of the metal cover 79 can be altered, and
the metal cover 79 can directly contact the mesh-shaped conductive
layer 73.
[0181] In the PDP display apparatus of the invention, since the
optical filter generally has a plastic film as a substrate, it is
possible to directly attach the optical filter to the surface of
the glass plate of the PDP as described above. Therefore, PDP
itself can be reduced in weight, thickness and cost, especially in
case of using one transparent film. Further, compared with PDP
having a front plate of a transparent molded body in front of the
PDP, it is possible in the present invention to remove an air layer
having a low refractive index formed between PDP and a filter for
PDP. Therefore, the PDP of the invention does not have shortcomings
such as the increase of visible-rays reflectivity caused by the
interface reflection and the occurrence of the double reflection.
Thus, the PDP of the invention has an improved visibility.
[0182] Thus, the display provided with the optical filter of the
invention has excellent antireflection property and antistatic
property. Further, the display scarcely generates a radiation of
dangerous electromagnetic wave, and is easily viewable, free from
dust attachment, and safe.
[0183] The invention is illustrated in detail by using the
following Examples and Reference Example. The invention is not
restricted to the following Examples.
Example 1
Preparation of Optical Filter for Display
[0184] (1) Formation of Mesh-Shaped Metal Conductive Layer
[0185] A copper foil having thickness of 3 .mu.m was attached to
the entire surface of an adhesive layer (polyester polyurethane;
thickness of 20 nm) provided on the surface of a lengthy
polyethylene terephthalate film (thickness of 100 .mu.m, width of
600 mm, length of 100 m). The copper foil was processed into a
lattice pattern by means of photolithography.
[0186] The conductive layer on the surface of the film had line
width of 30 .mu.m, pitch of 127 .mu.m and opening ratio of 58%. The
mean thickness of the conductive layer (copper layer) was 3
.mu.m.
[0187] (2) Formation of Antiglare Layer
[0188] The following components:
TABLE-US-00001 Pentaerythritol triacrylate 200 parts by weight (NK
ester A-TMM-3L, Shin Nakamura Chemical Co., Ltd., refractive index:
1.49) ITO (mean particle size: 150 nm) 20 parts by weight Acrylic
beads (mean particle size: 5 .mu.m, 3 parts by weight refractive
index: 1.49, trade name: MX-500, Soken Chemical & Engineering
Co., Ltd.) IPA 100 parts by weight Cyclohexanone 100 parts by
weight Irgacure 184 (Available from Ciba specialty 6 parts by
weight chemicals)
were mixed with each other to form a coating liquid, which was
applied to the entire surface of the mesh-shaped metal conductive
layer with a bar coater, and cured by UV irradiation. Hence, an
antiglare layer having thickness of 4 .mu.m (refractive index:
1.48) was formed on the mesh-shaped metal conductive layer.
[0189] Thus, an optical filter for a display was obtained.
Example 2
Preparation of Optical Filter for Display
[0190] (1) Formation of Mesh-Shaped Metal Conductive Layer
[0191] A copper foil having thickness of 10 .mu.m was attached on
an entire surface of an adhesive (polyester polyurethane, thickness
of 20 nm) layer provided on a lengthy polyethylene terephthalate
film (thickness of 100 .mu.m, width of 600 mm, length of 100 m).
The copper foil was processed into a lattice pattern by means of
photolithography.
[0192] The conductive layer on the surface of the film had line
width of 30 .mu.m, pitch of 127 .mu.m and opening ratio of 58%. The
mean thickness of the conductive layer (copper layer) was 10
.mu.m.
[0193] (2) Formation of Sealing Layer and Antiglare Layer
[0194] The following components:
TABLE-US-00002 Pentaerythritol triacrylate 200 parts by weight (NK
ester A-TMM-3L, Shin-Nakamura Chemical Co., Ltd., refractive index:
1.49) ITO (mean particle size: 150 nm) 20 parts by weight Acrylic
beads (mean particle size: 3 .mu.m, 3 parts by weight refractive
index: 1.49, trade name: MX-300TA, Soken Chemical & Engineering
Co., Ltd.) IPA 100 parts by weight Cyclohexanone 100 parts by
weight Irgacure 184 (Available from Ciba specialty 6 parts by
weight chemicals)
were mixed with each other to form a coating liquid 1.
Subsequently, a coating liquid 2 was prepared in the same manner as
above, except that the acrylic beads were not used.
[0195] The coating liquid 2 was applied to the entire surface of
the mesh-shaped metal conductive layer with a bar coater, and cured
by UV irradiation. Hence, a sealing layer having thickness of 10
.mu.m was formed on (spaces of) the mesh-shaped metal conductive
layer. Subsequently, the coating liquid 1 was applied to the
surfaces of the mesh-shaped metal conductive layer and the sealing
layer with the bar coater, and cured by UV irradiation. Hence, an
antiglare layer having thickness of 2 .mu.m was formed on the
mesh-shaped metal conductive layer.
[0196] Thus, an optical filter for a display was obtained.
Example 3
Formation of Optical Filter for Display
[0197] The following layers ware further formed on the optical
filter obtained in Example 1. A coating liquid of the following
formulation for preparing an anchor coat layer was applied to an
adhesive layer provided on the surface of a lengthy polyethylene
terephthalate film (thickness of 100 .mu.m, width of 600 mm, length
of 100 m). After drying, an anchor coat layer with a thickness of
0.2 .mu.m was formed.
TABLE-US-00003 (Formulation) Polyester solution (solid content: 40%
by weight, 100 parts by weight Trade name: AD335AE, available from
Toyo Morton Co., Ltd) Polyisocyanate solution (solid content: 53%
by 6.5 parts by weight weight Trade name: CAT-10L, available from
Toyo Morton Co., Ltd) Toluene 250 parts by weight Methyl ethyl
ketone 250 parts by weight
[0198] A 20% of polyvinyl alcohol aqueous solution was printed in
dot pattern on the resultant anchor coat layer. Each dot had a
square shape having a length of each side of 127 .mu.m. The
distance between the dots was 30 .mu.m, and the arrangement of the
dots was in the form of a square grid (lattice). The print
thickness was approx. 4 .mu.m after drying.
[0199] On the PET film having the above dot pattern, copper was
vacuum-deposited to form a copper layer having mean thickness of 3
.mu.m. Subsequently, the PET film having dot pattern and copper
layer was immersed in room-temperature water and the dots were
dissolved and removed by rubbing the same with a sponge, and then
the PET film was rinsed with water, dried to form a mesh-shaped
conductive layer on the entire surface of the PET film.
[0200] The metal conductive layer on the PET film showed pattern of
square grid (mesh) precisely corresponding to negative pattern for
the dot pattern. The line width of the mesh was 30 .mu.m, the pitch
was 127 .mu.m, and the opening ratio was 58%. Further mean
thickness of the conductive layer (copper layer) was 3 .mu.m.
[0201] (2) Formation of Antiglare Layer
[0202] The following components:
TABLE-US-00004 Pentaerythritol triacrylate 200 parts by weight (NK
ester A-TMM-3L, available from Shin Nakamura Chemical Co., Ltd.,
refractive index: 1.49) ITO (mean particle size: 150 nm) 20 parts
by weight Acrylic beads (mean particle size: 5 .mu.m, 3 parts by
weight refractive index: 1.49, Trade name: MX-500, available from
Soken Chemical & Engineering Co., Ltd.) IPA 100 parts by weight
Cyclohexanone 100 parts by weight Irgacure 184 (Available from Ciba
specialty 6 parts by weight chemicals)
were mixed with each other to form a coating liquid. The coating
liquid was applied to the entire surface of the mesh-shaped metal
conductive layer with a bar coater, and cured by UV irradiation.
Hence, an antiglare layer having thickness of 4 .mu.m (refractive
index: 1.48) was formed on the mesh-shaped metal conductive
layer.
[0203] Thus, an optical filter for a display was obtained.
Reference Example 1
Formation of Optical Filter for Display
[0204] An optical filter for a display was obtained in the same
manner as in Example 3 except that CAT-10L was not used in
formulation of an anchor coat layer.
[Evaluation of Optical Filter]
[0205] (1) The height from the surface of the film to the surface
of the antiglare layer (the thickness of the antiglare layer), and
the height from the surface of the antiglare layer to the surface
of the projected particles.
[0206] The height from the surface of the film to the surface of
the anti-glare layer (the thickness of the antiglare layer) was
calculated from a difference obtained by measuring the surface of
the film and the surface of the antiglare layer formed on the
surface of the film by using a surface roughness meter (trade name:
SURFCOM480A available from Tokyo Seimitsu Co., Ltd) in accordance
with JIS B0601-2001.
[0207] The height from the surface of the antiglare layer to the
surface of the exposed particles can be calculated from a profile
curve obtained by measuring by using the surface roughness meter
(trade name: SURFCOM480A available from Tokyo Seimitsu Co., Ltd) in
accordance with JIS B0601-2001. This was carried out at the
measurement length of 2 mm.
[0208] (2) Transmission Image Sharpness
[0209] Transmission image sharpness was determined in accordance
with JIS-K-7105.
[0210] (3) Reflection Image Sharpness (Reflection Angle: 45
Degrees)
[0211] Reflection image sharpness was determined in accordance with
JIS-K-7105.
[0212] (4) Haze Value of Optical Filter
[0213] The haze value was determined by using Full Automatic
Direct-Reading Haze Computer (HGM-2DP; manufactured by Suga
Shikenki K.K.) according to JIS K 7105 (1981).
[0214] (5) Ra of Antiglare Layer
[0215] Ra of the antiglare layer was determined in the same manner
as in (1).
[0216] The obtained results were shown in Table 1.
TABLE-US-00005 TABLE 1 Height of projected Trans- Thickness
particles mission Reflection of anti- (projection image image Haze
Ra glare layer ratio %) sharpness sharpness (%) (.mu.m) Example 1 4
.mu.m 1 .mu.m 182 56 3.5 0.15 -20% Example 2 2 .mu.m 1 .mu.m 190 50
3 0.11 -33% Example 3 4.3 .mu.m 0.7 .mu.m 188 50 3.5 0.13 -14%
Example 4 4.3 .mu.m 0.7 .mu.m 188 50 10 0.13 -14%
[0217] PDP filters obtained in Examples 1 to 3 had comparable
transparency and electromagnetic wave shielding property, with
respect to the conventional filter. Moreover, the PDP filters of
Examples 1 to 3 showed an excellent productivity in the PDP
manufacture, that was superior to the conventional filter.
[0218] Another optical filter was produced as follows, which
additionally had further functional layers in the optical filter of
Example 3.
Example 4
Formation of Optical Filter for Display
[0219] The following layers were further included in the optical
filter obtained in Example 3.
[0220] (3) Formation of Low Refractive Layer
The following components:
TABLE-US-00006 OPSTAR JN-7212 (Available from JSR 100 parts by
weight Corporation) Methyl ethyl ketone 117 parts by weight Methyl
isobutyl ketone 117 parts by weight
were mixed with each other to form a coating liquid. The coating
liquid was applied to the abovementioned hard coat layer with a bar
coater, and dried in an oven at 80.degree. C. for five minutes, and
then cured by UV irradiation. Hence, a low refractive layer having
thickness of 90 nm (refractive index: 1.42) was formed on the hard
coat layer.
[0221] (4) Formation of Near-Infrared Absorption Layer (Having
Color Hue Adjusting Function)
The following components:
TABLE-US-00007 Polymethyl methacrylate 30 parts by weight TAP-2 0.4
parts by weight (available from Yamada Chemical Co., Ltd.) Plast
Red 8380 0.1 part by weight (available from Arimoto Chemical Co.,
Ltd.) CIR-1085 1.3 parts by weight (available from Japan Carlit
Co., Ltd.) IR-10A 0.6 parts by weight (available from Nippon
Syokubai Co., Ltd.) Methyl ethyl ketone 152 parts by weight Methyl
isobutyl ketone 18 parts by weight
were mixed with each other to form a coating liquid. The coating
liquid was applied to entirely to a bottom surface of the
abovementioned polyethylene film with a bar coater, and dried in an
oven at 80.degree. C. for five minutes. Hence, a near-infrared
absorption layer (having color hue adjusting function) having
thickness of 5 .mu.m was formed on the polyethylene film.
[0222] (5) Formation of Transparent Adhesive Layer
The following components:
TABLE-US-00008 SK Dyne 1811L 100 parts by weight (Available from
Soken Chemical & Engineering Co., Ltd.) Hardener L-45 0.45
parts by weight (Available from Soken Chemical & Engineering
Co., Ltd.) Toluene 15 parts by weight Ethyl acetate 4 parts by
weight
were mixed with each other to form a coating liquid. The coating
liquid was applied to the abovementioned near-infrared absorption
layer with a bar coater. Hence, a transparent adhesive layer having
thickness of 25 .mu.m was formed on the near-infrared absorption
layer.
[0223] Thus, an optical filter for a display was obtained.
[0224] When the PDP filter obtained in Example 4 was attached to
PDP and an image was displayed on the PDP, a good image was
obtained.
* * * * *